Disclosed herein are methods comprising administering to a subject a combination comprising a therapeutically effective amount of at least one compound chosen of formula (I) in combination with a therapeutically effective amount of at least one paclitaxel compound chosen from paclitaxel, pharmaceutically acceptable salts thereof, and solvates of any of the foregoing.
The at least one compound of formula (I) is chosen from compounds having formula (I)
prodrugs, derivatives, pharmaceutically acceptable salts of any of the foregoing, and solvates of any of the foregoing.
Cancer fatalities in the United States alone number in the hundreds of thousands each year. Despite advances in the treatment of certain forms of cancer through surgery, radiotherapy, and chemotherapy, many types of cancer are essentially incurable. Even when an effective treatment is available for a particular cancer, the side effects of such treatment can be severe and result in a significant decrease in quality of life.
Most conventional chemotherapy agents have toxicity and limited efficacy, particularly for patients with advanced solid tumors. Conventional chemotherapeutic agents cause damage to non-cancerous as well as cancerous cells. The therapeutic index (i.e., a measure of a therapy's ability to discriminate between cancerous and normal cells) of such chemotherapeutic compounds can be quite low. Frequently, a dose of a chemotherapy drug that is effective to kill cancer cells will also kill normal cells, especially those normal cells (such as epithelial cells and cells of the bone marrow) that undergo frequent cell division. When normal cells are affected by the therapy, side effects such as hair loss, suppression of hematopoiesis, and nausea can occur. Depending on the general health of a patient, such side effects can preclude the administration of chemotherapy, or, at least, be extremely unpleasant and uncomfortable for the patient and severely decrease quality of the remaining life of cancer patients. Even for cancer patients who respond to chemotherapy with tumor regression, cancers often quickly relapse, progress and form more metastasis after initial response to chemotherapy. Such recurrent cancers become highly resistant or refractory to chemotherapeutics. As discussed below, cancer stem cells (CSCs) or cancer cells with high stemness (stemness-high cancer cells) are responsible for the rapid tumor recurrence and resistance to further traditional chemotherapy.
CSCs are believed to possess the following four characteristics:
1. Stemness—As used herein, stemness means the capacity to self-renew and differentiate into cancer cells (Gupta P B et al., Nat. Med. 2009; 15(9):1010-1012). While CSCs are only a minor portion of the total cancer cell population (Clarke M F, Biol. Blood Marrow Transplant. 2009; 11(2 suppl 2):14-16), they can give rise to heterogeneous lineages of cancer cells that make up the bulk of the tumor (see Gupta et al. 2009). In addition, CSCs possess the ability to mobilize to distinct sites while retaining their stemness properties and thus regrowth of the tumor at these sites (Jordan C T et al. N. Engl. J. Med. 2006; 355(12):1253-1261).
2. Aberrant signaling pathways—CSC stemness is associated with dysregulation of signaling pathways, which may contribute to their ability to regrow tumors and to migrate to distant sites. In normal stem cells, stemness signaling pathways are tightly controlled and genetically intact. In contrast, stemness signaling pathways in CSCs are dysregulated, allowing these cells to self-renew and differentiate into cancer cells (see Ajani et al. 2015). Dysregulation of stemness signaling pathways contributes to CSC resistance to chemotherapy and radiotherapy and to cancer recurrence and metastasis. Exemplary stemness signaling pathways involved in the induction and maintenance of stemness in CSCs include: JAK/STAT, Wnt/β-catenin, Hedgehog, Notch, and Nanog (Boman B M et al., J. Clin. Oncol. 2008; 26(17):2828-2838).
3. Resistance to traditional therapies—evidence suggests that CSCs possess resistance to conventional chemotherapy and radiation. While the detailed mechanism underlying such resistance is not well understood, the sternness pathways of CSCs (see Boman et al. 2008) together with the tumor microenvironment and aberrant regulation of signaling pathways (Borovski T. et al., Cancer Res. 2011; 71(3):634-639) may contribute to such resistance.
4. Ability to contribute to tumor recurrence and metastasis—although chemotherapy and radiation may kill most of the cells in a tumor, since CSCs are resistant to traditional therapies, the CSCs that are not eradicated may lead to regrowth or recurrence of the tumor either at the primary site or at distant sites (see Jordan et al. 2006). As mentioned above, CSCs may acquire the ability to mobilize to different sites and may maintain sternness at these sites through interactions with the microenvironment, allowing for metastatic tumor growth (see Boman et al. 2008).
The transcription factor Signal Transducer and Activator of Transcription 3 (referred to herein as Stat3) is a member of the Stat family, which are latent transcription factors activated in response to cytokines/growth factors to promote proliferation, survival, and other biological processes. Stat3 is an oncogene that can be activated by phosphorylation of a critical tyrosine residue mediated by growth factor receptor tyrosine kinases, including but not limited to, e.g., Janus kinases (JAKs), Src family kinases, EGFR, Abl, KDR, c-Met, and Her2. Yu, H. Stat3: Linking oncogenesis with tumor immune evasion in AACR 2008 Annual Meeting. 2008. San Diego, Calif. Upon tyrosine phosphorylation, the phosphorylated Stat3 (“pStat3”) forms homo-dimers and translocates to the nucleus, where it binds to specific DNA-response elements in the promoters of target genes, and induces gene expression. Pedranzini, L., et al. J. Clin. Invest., 2004. 114(5): p. 619-22.
In normal cells, Stat3 activation is transient and tightly regulated, lasting for example from 30 minutes to several hours. However, Stat3 is found to be aberrantly active in a wide variety of human cancers, including all the major carcinomas as well as some hematologic tumors. Persistently active Stat3 occurs in more than half of breast and lung cancers, colorectal cancers (CRC), ovarian cancers, hepatocellular carcinomas, multiple myelomas, etc., and in more than 95% of head/neck cancers. Stat3 plays multiple roles in cancer progression and is considered to be one of the major mechanisms for drug resistance to cancer cells. As a potent transcription regulator, Stat3 targets genes involved in cell cycle, cell survival, oncogenesis, tumor invasion, and metastasis, such as Bcl-xl, c-Myc, cyclin Dl, Vegf, MMP-2, and survivin. Catlett-Falcone, R., et al. Immunity, 1999. 10(1): p. 105-15; Bromberg, J. F., et al. Cell, 1999. 98(3): p. 295-303; Kanda, N., et al. Oncogene, 2004. 23(28): p. 4921-29; Schlette, E. J., et al. J Clin Oncol, 2004. 22(9): p. 1682-88; Niu, G., et al. Oncogene, 2002. 21(13): p. 2000-08; Xie, T. X., et al. Oncogene, 2004. 23(20): p. 3550-60. It is also a key negative regulator of tumor immune surveillance and immune cell recruitment. Kortylewski, M., et al. Nat. Med., 2005. 11(12): p. 1314-21; Burdelya, L., et al. J. Immunol., 2005. 174(7): p. 3925-31; and Wang, T., et al. Nat. Med., 2004. 10(1): p. 48-54.
Abrogation of Stat3 signaling by using anti-sense oligonucleotides, siRNA, dominant-negative form of Stat3, and/or the targeted inhibition of tyrosine kinase activity causes cancer cell-growth arrest, apoptosis, and reduction of metastasis frequency both in vitro and/or in vivo. Pedranzini, L., et al. J Clin. Invest., 2004. 114(5): p. 619-22; Bromberg, J. F., et al. Cell, 1999. 98(3): p. 295-303; Darnell, J. E. Nat. Med., 2005. 11(6): p. 595-96; and Zhang, L., et al. Cancer Res, 2007. 67(12): p. 5859-64.
Furthermore, Stat 3 may play a role in the survival and self-renewal capacity of CSCs across a broad spectrum of cancers. Therefore, an agent with activity against CSCs may hold great promise for cancer patients (Boman, B. M., et al. J. Clin. Oncol. 2008. 26(17): p. 2795-99).
As discussed above, CSCs are a sub-population of cancer cells (found within solid tumors or hematological cancers) that possess characteristics normally associated with stem cells. These cells can grow faster after reduction of non-stem regular cancer cells by chemotherapy, which may be the mechanism for quick relapse after chemotherapies. In contrast to the bulk of cancer cells, which are non-tumorigenic, CSCs are tumorigenic (tumor-forming). In human acute myeloid leukemia, the frequency of these cells is less than 1 in 10,000. Bonnet, D. and J. E. Dick. Nat. Med., 1997. 3(7): p. 730-37. There is mounting evidence that such cells exist in almost all tumor types. However, as cancer cell lines are selected from a sub-population of cancer cells that are specifically adapted to growth in tissue culture, the biological and functional properties of these cell lines can change dramatically. Therefore, not all cancer cell lines contain CSCs.
CSCs have stem cell properties such as self-renewal and the ability to differentiate into multiple cell types. They persist in tumors as a distinct population and they give rise to the differentiated cells that form the bulk of the tumor mass and phenotypically characterize the disease. CSCs have been demonstrated to be fundamentally responsible for carcinogenesis, cancer metastasis, cancer recurrence, and relapse. CSCs are also called, for example, tumor initiating cells, cancer stem-like cells, stem-like cancer cells, highly tumorigenic cells, or super malignant cells.
CSCs are inherently resistant to conventional chemotherapies, which means they are left behind by conventional therapies that kill the bulk of tumor cells. As such, the existence of CSCs has several implications in terms of cancer treatment and therapy. These include, for example, disease identification, selective drug targets, prevention of cancer metastasis and recurrence, treatment of cancer refractory to chemotherapy and/or radiotherapy, treatment of cancers inherently resistant to chemotherapy or radiotherapy and development of new strategies in fighting cancer.
The efficacy of cancer treatments are, in the initial stages of testing, often measured by the amount of tumor mass they kill off. As CSCs form a very small proportion of the tumor cell population and have markedly different biologic characteristics than their differentiated progeny, the measurement of tumor mass may not select for drugs that act specifically on the stem cells. In fact, CSCs are radio-resistant and refractory to chemotherapeutic and targeted drugs. Normal somatic stem cells are naturally resistant to chemotherapeutic agents-they have various pumps (e.g., multidrug resistance protein pump) that efflux drugs, higher DNA repair capability, and have a slow rate of cell turnover (chemotherapeutic agents naturally target rapidly replicating cells). CSCs, being the mutated counterparts of normal stem cells, may also have similar functions that allow them to survive therapy. In other words, conventional chemotherapies kill differentiated (or differentiating) cells, which form the bulk of the tumor that is unable to generate new cells. A population of CSCs that gave rise to the tumor could remain untouched and cause a relapse of the disease. Furthermore, treatment with chemotherapeutic agents may only leave chemotherapy-resistant CSCs, so that the ensuing tumor will most likely also be resistant to chemotherapy. Cancer stem cells have also been demonstrated to be resistant to radiation therapy (XRT). Hambardzumyan, et al. Cancer Cell, 2006. 10(6): p. 454-56; and Baumann, M., et al. Nat. Rev. Cancer, 2008. 8(7): p. 545-54.
Since surviving CSCs can repopulate the tumor and cause relapse, anti-cancer therapies that include strategies against CSCs hold great promise. Jones R J et al., J Natl Cancer Inst. 2004; 96(8):583-585. By targeting CSC pathways, it may be possible to treat patients with aggressive, non-resectable tumors and refractory or recurrent cancers as well as prevent tumor metastasis and recurrence. Development of specific therapies targeting CSC pathways, therefore, may improve the survival and quality of life of cancer patients, especially those patients suffering from metastatic disease. Unlocking this untapped potential may involve the identification and validation of pathways that are selectively important for CSC self-renewal and survival. Though multiple pathways underlying tumorigenesis in cancer and in embryonic stem cells or adult stem cells have been elucidated in the past, pathways for cancer stem cell self-renewal and survival are still sought.
Methods for identification and isolation of CSCs have been reported. The methods used mainly exploit the ability of CSCs to efflux drugs or have been based on the expression of surface markers associated with cancer stem cells.
For example, since CSCs are resistant to many chemotherapeutic agents, it is not surprising that CSCs almost ubiquitously overexpress drug efflux pumps such as ABCG2 (BCRP-1), and other ATP binding cassette (ABC) superfamily members. Ho, M. M., et al. Cancer Res., 2007. 67(10): p. 4827-33; Wang, J., et al. Cancer Res., 2007. 67(8): p. 3716-24; Haraguchi, N., et al. Stem Cells, 2006. 24(3): p. 506-13; Doyle, L. A. and D. D. Ross. Oncogene, 2003. 22(47): p. 7340-58; Alvi, A. J., et al. Breast Cancer Res., 2003. 5(1): p. R1-R8; Frank, N. Y., et al. Cancer Res., 2005. 65(10): p. 4320-33; and Schatton, T., et al. Nature, 2008. 451(7176): p. 345-49. Accordingly, the side population (SP) technique, originally used to enrich hematopoetic and leukemic stem cells, was also employed to identify and isolate CSCs. Kondo, T., et al. Proc. Natl Acad. Sci. USA, 2004. 101(3): p. 781-86. This technique, first described by Goodell et al., takes advantage of differential ABC transporter-dependent efflux of fluorescent dyes such as Hoechst 33342 to define a cell population enriched in CSCs. Doyle, L. A. and D. D. Ross. Oncogene, 2003. 22(47): p. 7340-58; and Goodell, M. A., et al. J. Exp. Med., 1996. 183(4): p. 1797-806. Specifically, the SP is revealed by blocking drug efflux with verapamil, at which point the dyes can no longer be pumped out of the SP.
Efforts have also focused on finding specific markers that distinguish CSCs from the bulk of the tumor. Markers originally associated with normal adult stem cells have been found to also mark CSCs and co-segregate with the enhanced tumorigenicity of CSCs. Commonly expressed surface markers by the CSCs include CD44, CD133, and CD166. Al-Hajj, M., et al. Proc. Natl Acad. Sci. USA, 2003. 100(7): p. 3983-88; Collins, A. T., et al. Cancer Res., 2005. 65(23): p. 10946-51; Li, C., et al. Cancer Res., 2007. 67(3): p. 1030-37; Ma, S., et al. Gastroenterology, 2007. 132(7): p. 2542-56; Ricci-Vitiani, L., et al. Nature, 2007. 445(7123): p. 111-15; Singh, S. K., et al. Cancer Res., 2003. 63(18): p. 5821-28; and Bleau, A. M., et al., Neurosurg. Focus, 2008. 24(3-4): p. E28. Sorting tumor cells based primarily upon the differential expression of these surface marker(s) have accounted for the majority of the highly tumorigenic CSCs described to date. Therefore, these surface markers are validated for identification and isolation of CSCs from the cancer cell lines and from the bulk of tumor tissues.
By using aiRNA (asymmetric RNA duplexes), potent Stat3 selective silencing has been achieved in stemness-high cancer cells. This Stat3 silencing may lead to downregulation of cancer cell stemness, and/or inhibition of stemness-high cancer cell survival and self-renewal.
In some embodiments, the at least one compound of formula (I) is an inhibitor of CSC growth and survival. According to U.S. Pat. No. 8,877,803, the compound of formula (I) inhibits Stat3 pathway activity with a cellular IC50 of ˜0.25 μM. The at least one compound of formula (I) may be synthesized according to U.S. Pat. No. 8,877,803, for example, Example 13. In some embodiments, the at least one compound of formula (I) is used in a method of treating cancers. According to PCT Patent Application No. PCT/US2014/033566, Example 6, the at least one compound of formula (I) was chosen to enter a clinical trial for patients with advanced cancers. The disclosures of U.S. Pat. No. 8,877,803 and PCT Patent Application No. PCT/US2014/033566 are incorporated herein by reference in their entireties.
We have surprisingly discovered that patients with higher expression levels of Stat3 show prolonged overall survival after treatment with at least one compound of formula (I) in clinical trials. Thus, the higher the level of pStat3 found in a cancer patient before treatment, at least in CRC patients, the higher the overall survival (OS) upon administering a treatment comprising a compound of formula (I).
We also have surprisingly discovered that a treatment combination of at least one compound of formula (I) with at least one paclitaxel compound results in anti-tumor activity in subjects with certain types of cancer that progressed on prior taxane treatment.
In some embodiments, disclosed herein are methods for treating cancer that had progressed on at least one prior taxane regimen comprising administering to a subject in need thereof:
a therapeutically effective amount of at least one compound of formula (I) chosen from compounds having formula (I):
prodrugs, derivatives, pharmaceutically acceptable salts of any of the foregoing, and solvates of any of the foregoing, and
a therapeutically effective amount of at least one paclitaxel compound chosen from paclitaxel, pharmaceutically acceptable salt thereof, and solvates of any of the foregoing.
The at least one compound of formula (I) and the at least one paclitaxel compound may be administered to a subject simultaneously and/or sequentially.
The at least one compound of formula (I) may be administered daily in a single or a divided dose. The at least one paclitaxel compound may be administered weekly.
In some embodiments, disclosed herein are methods for resensitizing a subject to at least one prior therapy regimen comprising administering to a subject in need thereof:
a therapeutically effective amount of at least one compound of formula (I) chosen from compounds having formula (I):
prodrugs, derivatives, pharmaceutically acceptable salts of any of the foregoing, and solvates of any of the foregoing. In some embodiments, the at least one prior therapy regimen is chosen from chemotherapy regimens. In some embodiments, the at least one prior therapy regimen chosen from taxane chemotherapy regimens. In some embodiments, disclosed herein are methods for resensitizing a subject to a taxane chemotherapy regimen comprising administering to a subject in need thereof:
a therapeutically effective amount of at least one compound of formula (I) chosen from compounds having formula (I):
prodrugs, derivatives, pharmaceutically acceptable salts of any of the foregoing, and solvates of any of the foregoing.
In some embodiments, a kit is disclosed that comprises (1) at least one compound chosen from compounds having formula (I), prodrugs, derivatives, pharmaceutically acceptable salts of any of the foregoing, and solvates of any of the foregoing, and (2) at least one paclitaxel compound chosen from paclitaxel, pharmaceutically acceptable salts thereof, and solvates of any of the foregoing, together with instructions for administration and/or use.
Aspects and embodiments of the present disclosure are set forth or will be readily apparent from the following detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to be restrictive of the claims.